The farmer from Mohanpura village in central India's Madhya Pradesh state had seen unseasonably heavy rains and hailstorms destroy crop after crop, while he fell deeper into debt.

Finally, last August, with no way to feed his family, Singh felt he had only one choice: He sold his two sons to a shepherd for a year of labour, in exchange for Rs 35,000 ($500).

"I was in no position to repay the debt and needed more money to make ends meet and plant a further crop," Singh said in an interview in Mohanpura.

He made the decision, he said, despite knowing "it was illegal and they could be abused and forced to work in cruel conditions."

Worsening crop failures, brought on by extreme weather, are leading to increasing financial desperation in Madhya Pradesh - and a rash of suicides and child trafficking, officials say.

FIVE CHILDREN RESCUED

According to Rajnish Shrivastava, the district collector of Harda district, authorities rescued five children from forced labour in April, all from Khargone and Harda districts.

Officials believe there could be many other cases of farmers trading their children for money, he said.

"It is a matter of concern that farmers have been forced to sell their kids to repay their debts," he said.

"We can't allow children to be abused and trafficked in this way."

Eight months after being sold into labour, Singh's children were among the five rescued, Shrivastava said. Sumit, 12, and Amit, 11, fled from the shepherd and were taken to a local shelter, according to officials.

Initially reluctant to return to their family for fear of how their parents would react, the boys are now back home, officials said.

"Our job was to look after the sheep and other animals," Amit told the Thomson Reuters Foundation. "(The shepherd) thrashed us over trivial issues. We were not given even two meals a day. As things became intolerable we took courage and fled."

Authorities have ordered an investigation, while the shepherds who allegedly bought the five rescued children have been charged with the unlawful confinement of children and are awaiting trial, Shrivastava said.

According to Vishnu Jaiswal, director of the Harda branch of children's charity Childline, officials from his charity and from the government will visit the rescued children's families from time to time to ensure they are being well looked after.

"Trading our children was wrong but we were forced to do this just to stay alive," Sumit and Amit's mother, Manibai, said in an interview. "Otherwise, like many other farmers, we too would have been forced to commit suicide."

DEBT SUICIDES

India has seen an alarming rate of suicide among farmers, as extreme weather continues to cause unprecedented crop losses in many parts of the country.

According to state government figures, Madhya Pradesh state was among the hardest hit this year, with over 570,000 hectares (1.4 million acres) of rabi crops - wheat and other crops that are sown in winter and harvested in spring - devastated by unusually heavy rains and hailstorms.

Around 40 farmers committed suicide or died from stress-related causes in Madhya Pradesh alone between February and May 2015, state police and revenue officials said.

The situation is difficult in parts of other states as well, including Maharashtra, Rajasthan, and Punjab, said Sachin Jain, an activist with the Right to Food campaign, an informal network of organisations working to ensure a right to food in India.

GOVERNMENT HELP?

"It is very serious," said Gauri Shankar Bisen, Minister of Agriculture for Madhya Pradesh. "We are investigating the matter and have directed district collectors to provide compensation to farmers as soon as possible."

The governments of most Indian states affected by extreme weather have announced relief packages for farmers. But activists claim the process of delivering relief is taking too long, with authorities still assessing the damage in some regions.

Corruption in some areas means farmers see very little financial aid, Jain said.

"The compensation amount is often far from enough for the farmers to pay off their debts," said the activist.

"When farmers aren't able to get loans from banks, they're forced to borrow from private moneylenders who charge interest at exorbitant rates. They are painfully aware that they won't get relief."

Bisen, from the Ministry of Agriculture, said the government is working hard to ensure relief gets to farmers as quickly as possible.

"We try our best to provide relief to the farmers at the earliest. There are various formalities which have to be completed. There were some allegations of corruption against officials which have to be investigated," he said.

But activists say the government needs to get money to farmers faster, or more cases of farmers selling children may come to light.

"Farmers are in dire straits," said Jain. "That's why they take such extreme steps." (Reporting by Shuriah Niazi; editing by Laurie Goering)